BE1030039B1 - FLOW SEPARATOR IN A TURBOMACHINE - Google Patents

Abstract

The invention relates to a turbomachine (1) comprising a splitter nozzle (36) splitting an air flow (F) into a primary annular flow (F2) and a secondary annular flow (F2); and an annular row of rotor vanes (40) arranged upstream of the splitter nose (36), each vane (40) having a lower surface and an upper surface; the turbomachine (1) being remarkable in that at least one of the blades (40) has a fin (42) extending circumferentially from its lower surface or from its upper surface, the circumferential width (E) of the fin (42) being at least twice the maximum circumferential thickness (A) of the blade (40).

Description

Description

FLOW SEPARATOR IN A TURBOMACHINE

Domain

The invention relates to the design of a turbomachine and more particularly a multi-flow turbomachine.

Prior art

Double-flow turbomachines generally have a fan at the inlet which is followed by a separation nozzle. The splitter splits the main flow into two flows, only one of which goes through the compressors, the combustion chamber and the turbines.

To limit vibrations, document FR 2 440 466 A1 describes fan blades fitted with fins providing it with vibration damping.

Document FR 2 867 506 shows stator vanes with ribs to attenuate vibrations. These blades are arranged upstream of support arms at a significant distance from a flow separation.

These fins do not prevent the separation nozzle from being the site of turbulence, risks of flow separation, and therefore loss of efficiency for the turbojet engine. These losses, which may be negligible for a cold, slow flow and at low pressure, become significant for a hotter, faster and/or higher pressure flow. These higher pressure, speed and temperature conditions may appear under certain flight conditions and/or at certain locations of the turbomachine, in particular downstream of one or more rotating elements.

Summary of the invention

Technical problem

The invention aims to solve the drawbacks of turbomachines of the state of the art. In particular, the invention aims to propose a design which allows a separation of an air flow without penalizing the efficiency of the turbomachine, and this, whatever the conditions of pressure, temperature and speed of the flow to be separated. .

Technical solution

The invention relates to a turbomachine comprising: a splitter nozzle splitting an inlet air flow into a primary flow and a secondary flow; and an annular row of rotor vanes arranged upstream of the separation nozzle, each vane having an intrados and an extrados; the turbomachine being remarkable in that at least one of the blades has a fin extending circumferentially from its lower surface or from its upper surface, the circumferential width of the fin being at least twice the maximum circumferential thickness of the blade .

The fin (or "fin" or "blade") has a function of guiding an air flow and as such can have a leading edge (that is to say a rounded edge and not a frontal surface which would present a resistance to the aerodynamic flow of the air), an upper and lower surface which can be rounded or curved in the manner of an intrados or an extrados, and a trailing edge.

The row of blades can be arranged "directly" upstream of the separation nozzle, which means that no fixed or mobile element is inserted axially between the blades and the nozzle. Alternatively, an element (fixed or mobile) can be inserted between the blades and the nozzle.

From the separation spout extends an external surface, for internal guiding of the secondary flow, and an internal surface, for external guiding of the primary flow.

The inflow is thus pre-guided by the fin before being split into two flows.

This pre-guiding reduces the risks of turbulence or separation of the flow and allows an improvement in the efficiency of the turbomachine, independently of the pressure and temperature conditions of the flow.

According to an advantageous embodiment of the invention, each blade defines, with a blade directly adjacent circumferentially, an inter-blade spacing, and the circumferential width of the fin is equal to at least 30% of the inter-blade spacing, preferably at least 50% and more preferably the circumferential width of the fin is close to 100% of the inter-blade spacing.

According to an advantageous embodiment of the invention, in the vicinity of the separation nozzle, the primary flow and the secondary flow flow along two respective main directions of flow, respectively defining a primary angle and a secondary angle, with respect to the axis of rotation of the blades, and the fin comprises a trailing edge which guides the inflow according to a trailing angle which is between the primary angle and the secondary angle. A compromise is thus found to limit the aerodynamic losses even when the two flows downstream of the nozzle are very divergent. This orientation of the fin also gives flexibility for the design of the veins downstream of the blades, allowing in particular a steep gooseneck at the outlet of a compressor, and therefore a high compression ratio and better efficiency.

According to an advantageous embodiment of the invention, the vanishing angle of the trailing edge of the fin is closer to the secondary angle than to the primary angle.

According to an advantageous embodiment of the invention, the radial thickness of the fin varies from upstream to downstream and in particular the thickness generally increases from upstream to downstream. This also makes it possible to properly pre-direct the input stream to the primary and secondary streams.

According to an advantageous embodiment of the invention, the fin comprises a first trailing edge and a second trailing edge, the two trailing edges being radially separated by a cavity. Thus, the trailing edges can be oriented as close as possible to the flow directions of the primary and secondary flows.

According to an advantageous embodiment of the invention, an auxiliary fin is arranged in axial and circumferential overlap of the fin. This design makes it possible to properly pre-guide the inlet flow without increasing the weight of the rotating assembly, further allowing a gain in efficiency.

According to an advantageous embodiment of the invention, an auxiliary blade extends radially externally and/or internally from the fin, preferably over a height greater than 15% of the height of the blades. The fin thus offers the opportunity to compress the flow more, or even to compress it in a heterogeneous way between the primary flow and the secondary flow, thus adapting the optimal compression rate for the primary and secondary flows and thus allowing a gain in efficiency. .

Advantageously, the auxiliary vane is welded to the fin. It can for example be pre-positioned in a notch provided for this purpose on the fin, then welded.

According to an advantageous embodiment of the invention, the fin extends from the lower surface of a first blade to the upper surface of a second blade, circumferentially directly adjacent to the first blade. Thus, the entire inter-blade space is occupied by the fin, thus forcing the particles of the flow to engage either towards the primary flow or towards the secondary flow.

According to an advantageous embodiment of the invention, the fin extends from the lower surface of a first blade and another fin extends from the upper surface of a second blade, the two fins being preferentially at the same radial height and separated by a circumferential gap. The gap can be very small and actually form an assembly clearance. The gap can be linear and possibly axial. It can alternatively be curved, in particular parallel to the lower surface or the upper surface to follow the camber of the blades. Alternatively, the two fins from adjacent blades can overlap circumferentially.

According to an advantageous embodiment of the invention, the fin has irregularities on its radially outer surface and/or on its radially inner surface, the irregularities being in particular of the three-dimensional contouring type. These irregularities are bumps and/or hollows, the height or depth of which are of a very low order of magnitude compared to the dimensions of the fin. These irregularities further improve the guiding of the flow and therefore the efficiency of the turbomachine.

According to an advantageous embodiment of the invention, the axial length of the fin is less than that of the blades. Alternatively, the axial length of the fin can be greater than or identical to that of the blade carrying it.

According to an advantageous embodiment of the invention, the transverse profile of the fin has a camber and/or a point of inflection. Alternatively, the profile can be linear, presenting a constant angle from the entry angle of the leading edge and to the exit angle of the trailing edge. Depending on the geometry of the primary and secondary flow veins, one or the other of the designs is more or less advantageous. In particular, a camber makes it possible to conduct a greater volume of air towards one or the other of the flows to favor a greater compression rate there.

According to an advantageous embodiment of the invention, the row of blades comprises a plurality of fins, of which at least two fins differ in their profile, their radial position, their circumferential width, their thickness, their shape and/or their method of manufacturing. 5 According to an advantageous embodiment of the invention, the fin is welded to the blade from which it extends or the fin and the blade are machined together in the same blank.

According to an advantageous embodiment of the invention, all the blades of the row of blades and the fin(s) are one-piece, obtained by machining a single blank or obtained by additive manufacturing.

According to an advantageous embodiment of the invention, the fin has a free end whose axial length is at least 30% of the chord of the blade, preferably at least 70%, more preferably approximately 80% of the chord of the blade. 'dawn.

According to an advantageous embodiment of the invention, the fin has a trailing edge whose radial position corresponds to the radius of the separation beak.

The separation nose has a circular edge that forms its upstream end, rounded or not, and which can define the radius of the nose. When the edge is very rounded, the radius of the circular edge is no longer a simple value but a range of values (median value +/- the radius of the rounding), the trailing edge of the fin being located at a radial position within this range of values.

Advantages of the invention

The invention is particularly advantageous in that it makes it possible to split a stream into several streams (two or more) while limiting the effects on the efficiency of the engine.

An additional advantage of the presence of a fin is the protection of the veins in the event of ingestion of foreign objects in the engine.

The pre-guiding of the flows also allows greater freedom in the trajectory of the downstream veins and in particular a more abrupt gooseneck, because the flow which enters the gooseneck can be pre-guided and present less risk of detachment .

Then, the secondary flow (respectively primary) can be “energized”, i.e. accelerated and/or compressed more than the primary flow (resp. secondary).

Description of the drawings

Figure 1 is a sectional view of a turbomachine;

Figure 2 illustrates the separation of a stream;

Figures 3A to 3D show different cross-sectional profiles of the fin;

Figure 4 is an isometric view of the blade and its fin;

Figures 5A and 5B show two examples of fins viewed radially;

Lafigure6 is an isometric view of the impeller fitted with fins on all the blades;

Figure 7 shows a variant with auxiliary vanes.

Description of an embodiment

In the following description, the terms “internal” and “external” refer to positioning relative to the axis of rotation of a turbomachine. The axial direction corresponds to the direction along the axis of rotation of the turbomachine. The radial direction is perpendicular to the axis of rotation. Upstream and downstream are to be considered with reference to the flow direction of a flow in the turbomachine.

The figures show the elements schematically and are not drawn to scale. In particular, certain dimensions are enlarged to facilitate reading of the figures.

Figure 1 shows a schematic sectional view of a turbomachine 1. An inner casing 2 guides a primary flow F1 which successively passes through compressors 4 (low and high pressure), a combustion chamber 6 and turbines 8 (high and low pressure), before escaping through a nozzle 10. The combustion energy drives the turbines 8 in rotation. The turbines 8 drive the compressors 4, directly by means of transmission shafts, or indirectly by means of reducers.

The turbines 8 also rotate a rotor 12 with fan blades 14 which set in motion a secondary flow F2. Most of the thrust of the turbomachine is generated by the propulsion of the flow F2 by the rotor 12, which is said to be “propulsive”. The primary flow F1 is used as an oxidizer to ensure the rotation of the turbines and the rotor 12.

A fairing 16 and a nacelle 18 delimit a passage 34 which is traversed by the secondary flow F2.

Structural arms 20 take up the forces between the nacelle 18 and the engine casing 2.

An annular row of stator vanes 22 (“outlet guide vanes”, OGV) can be arranged downstream of the rotor 12 to straighten the flow F2.

A reducer 23 can also greatly reduce the speed of rotation (between the turbines 8 and the blades 14).

The turbomachine 1 has a separation nozzle 36 to separate the air flow F into two annular flows.

Figure 2 schematically shows the separation of a flow into two annular flows.

An input stream F is split into a primary stream F1 and into a secondary stream F2. The primary F1 and secondary F2 flows respectively flow in an annular vein 32, 34. These flows can correspond to the primary and secondary flows of FIG. 1 or to other flows separated from each other in the turbomachine.

The separation of the flows is carried out by a separation nose 36 of circular shape around the axis of the turbomachine X. The separation nose 36 may have an upstream circular edge which may be a sharp or rounded edge. It is arranged directly upstream of a surface 34.1 which internally guides the secondary flow

F2 and a surface 32.1 which externally guides the primary flow F1. These two surfaces 32.1, 34.1 can be approximately truncated cones in the vicinity of the spout 36. The flows F1 and F2 have a main direction of flow which is oriented along the angles a, and a, in the vicinity of the spout 36. angle a, can be between -60° and +15°. The angle a" can be between -15° and +60°, while naturally being greater than 04.

The separating nose 36 or its circular edge defines a radius R up to the X axis.

Directly upstream of the nozzle 36 (or indirectly by means of one or more fixed or rotating elements) is located a rotating assembly in the form of a movable wheel 38 equipped with an annular row of blades 40 extending from an internal disc 41. The impeller 38 may be (but need not be) the rotor 12 of Figure 1 and the blades 40 may be the blades 14.

At least one fin 42 extends circumferentially from a blade 40 of the impeller 38. Figure 2 highlights the fact that the fin 42 comprises a leading edge 42.1 and a trailing edge 42.2. The latter can be located at a radial height R.

Figure 2 also highlights the vanishing angle a which corresponds to the orientation of the flow F in the vicinity of the trailing edge 42.2 of the fin 42. This angle is between a, and A”.

Figures 3A to 3D show different transverse profiles that fin 42 may have. Fin 42 extends from its leading edge 42.1 to its trailing edge 42.2. A radially lower surface 42.3 and a radially upper surface 42.4 define the fin 42 radially. The thickness e of the fin 42 is the shortest distance between the inner 42.3 and outer 42.4 surfaces for a given axial position. These surfaces can be provided with shapes helping to guide the flow (“contouring”) and thus presenting local variations in thickness.

In FIG. 3A, the fin 42 has an increasing radial thickness e and it extends axially beyond the blade 40. The length L of the blade 40 is smaller than the length | fin 42.

In Figure 3B, fin 42 is axially confined to blade 40.

In FIG. 3C, the fin 42 comprises a leading edge 42.1 and two trailing edges 42.2. A cavity 42.5 separates the two trailing edges 42.2.

In FIG. 3D, the fin 42 is arched with an inflection point and directs the flow F towards the secondary flow. A 42' auxiliary fin, also arched, helps pre-guiding the flow towards the primary flow. An inversion with the 42' auxiliary fin radially outward is also possible.

The embodiments of FIGS. 3C and 3D are particularly advantageous when the edge of beak 36 is very rounded, each of the two trailing edges 42.2 having a radial position which corresponds to the radius of the separating beak (see dotted lines in FIG. 3D).

It is understood that these examples can be modified and each aspect can be combined with another aspect of each of the examples. The different examples can be combined within the same row of blades, or even in the same inter-blade space.

FIG. 4 shows an isometric view of a blade 40. This blade 40 comprises a leading edge 40.1, a trailing edge 40.2, a lower surface 40.3 and a lower surface 40.4.

The maximum circumferential thickness of blade 40 is denoted A.

The fin 42 can be supported by the upper surface or the lower surface, or extend from both.

The fin 42 can be cantilevered, i.e. supported by a single vane, or extend from one vane 40 to a circumferentially adjacent vane. When it is cantilevered, it comprises a free end 42.6 which determines the circumferential width E of the fin. According to the invention, E is equal to at least 2 times A. Preferably E is much greater than A, for example at least 5 times greater.

Two neighboring blades define between them an inter-blade gap (denoted D in FIG. 5A). This can vary radially (the blade tips being farther apart than the blade roots). The width E of the fin can be at least 30% of this inter-blade gap and preferably the width E can be approximately equivalent to the inter-blade gap.

It is understood that when the fin 42 is supported by the two circumferentially neighboring blades, the circumferential width of the fin is equivalent to the inter-blade spacing.

The length | of the fin can be at least 30% of the axial length L of the vane or the chord C.

The blade 40 and the fin(s) 42 that it carries can be in one piece.

Optionally, several adjacent blades and their fins can be monobloc, thus describing an angular sector from a few degrees of angles to a few tens of degrees (for example 12 sectors of 30° forming the annular row of blades 40), or even up to at 360°.

The fins 42 may have a concentric curvature with the axis of the turbomachine. They can thus for example coincide with the position of the spout 36 over their entire circumferential width.

Figures 5A and 5B show two examples of fin 42 viewed in a plane perpendicular to a radius. FIG. 5A shows a single fin 42 with a leading edge 42.1 presenting an inflection point, to accompany the flow near the two blades. Figure 5B shows two fins 42 with a curved leading edge and trailing edge.

In a variant not shown, the leading and trailing edges are straight.

Figures 5A and 5B also highlight the gap 44. This can have a very small dimension, of the order of the mounting clearance. Alternatively, it may be larger to allow access for a welding tool (for orbital friction in particular).

Figure 5A also materializes the inter-blade gap D, which is the circumferential distance between the blades.

Figure 6 shows an isometric view of a bladed wheel 38 ("Blisk" for "Bladed disk") on which all the inter-blade spaces are occupied by a fin 42.

The blades 40 are fixed to a disk 41 by welding, or the blades are manufactured simultaneously with the disk, by machining the same raw material or by additive manufacturing. Any type of welding can be considered (electron beam welding, orbital friction, linear friction).

Similarly, the fins 42 are welded to the blades 40 or manufactured by machining or additive manufacturing.

Hybrid manufacturing (some fins welded, others machined; and/or some blades welded, others machined) is also possible.

FIG. 7 shows a partial view of another variant in which the fins 42 support auxiliary vanes 46. In the example illustrated, the auxiliary vanes 46 are “one” in number per inter-vane space and extend radially externally. It is understood that the number of auxiliary vanes carried by the fins and their orientations (external and/or internal) can be chosen according to the compression or the speed to be imparted independently to the primary or secondary flows. For example, one auxiliary vane may be directed inwards, and two auxiliary vanes outwards, the inner vane being circumferentially located midway between the outer vanes.

The radial length of the auxiliary vanes 46 is here about a quarter of the radial length of the vanes 40. They can also extend radially by a greater or lesser value, and this up to the value of the height of the vanes 40 As for the axial dimension, the auxiliary vanes 46 can extend between 50 and 100% of the axial length of the fins 42.

It should be noted that the invention is not limited to the examples described in the figures. Thus, several fins of different types can be provided in the same row of blades (for example, one without a gap, the other with, fins at different heights, with different cambers, etc.).

The distribution of the fins on the moving wheel can be symmetrical or not, and the fins can be evenly spaced angularly or irregularly.

Each technical characteristic of each illustrated example is applicable to the other examples. In particular, the number of blades, the number of fins and their arrangement, their transverse profile, their length, their camber, their shape, can be taken from one embodiment and applied to another.

Claims (17)

Claims 1. Turbomachine (1), comprising: - a separation nozzle (36) splitting an inlet air flow (F) into a primary annular flow (F1) and a secondary annular flow (F2); and - an annular row of rotor vanes (40) arranged upstream of the splitter nose (36), each vane (40) having an underside (40.3) and an upper side (40.4); the turbomachine (1) being characterized in that at least one of the blades (40) has a fin (42) extending circumferentially from its lower surface (40.3) or from its upper surface (40.4), the circumferential width (E) of the fin (42) being at least twice the maximum circumferential thickness (A) of the vane (40). 2. Turbomachine (1) according to claim 1, characterized in that each blade (40) defines, with a blade directly adjacent circumferentially, an inter-blade spacing, and the circumferential width (E) of the fin is equal to at least 30% of the inter-blade spacing, preferably at least 50% and more preferably the circumferential width (E) of the fin is close to 100% of the inter-blade spacing. 3. Turbomachine (1) according to claim 1 or 2, characterized in that in the vicinity of the separation nozzle (36), the primary flow (F1) and the secondary flow (F2) flow in two main directions of respective flows, respectively defining a primary angle (a4) and a secondary angle (a>), with respect to the axis (X) of rotation of the blades (40), and the fin (42) comprises a trailing edge (42.2 ) which guides the flow (F) according to a vanishing angle (a) which is between the primary angle (a4) and the secondary angle (θ2). 4. Turbomachine (1) according to claim 3, characterized in that the vanishing angle (a) of the trailing edge (42.2) of the fin (42) is closer to the secondary angle (d") than to the primary angle (04). 5. Turbomachine (1) according to one of the preceding claims, characterized in that the fin (42) comprises a first trailing edge (42.2) and a second trailing edge (42.2), the two trailing edges (42.2) being radially separated by a cavity (42.5). 6. Turbomachine (1) according to one of the preceding claims, characterized in that an auxiliary fin (42 ') is arranged in axial and circumferential overlap of the fin (42). 7. Turbomachine (1) according to one of the preceding claims, characterized in that an auxiliary blade (46) extends radially externally and/or internally from the fin (42), preferably over a height greater than 15% of the height of the blades (40). 8. Turbomachine (1) according to one of claims 1 to 7, characterized in that the fin (42) extends from the lower surface (40.3) of a first blade (40) to the upper surface (40.4 ) of a second vane (40), circumferentially directly adjacent to the first vane (40). 9. Turbomachine (1) according to one of claims 1 to 7, characterized in that the fin (42) extends from the lower surface (40.3) of a first blade (40) and another fin (42) extends from the extrados (40.4) of a second blade (40), the two fins (42) preferably being at the same radial height and separated by a circumferential gap (44). 10. Turbomachine (1) according to one of the preceding claims, characterized in that the fin (42) has irregularities on its radially outer surface (42.4) and/or on its radially inner surface (42.3), the irregularities being in particular of the three-dimensional contouring type. 11. Turbomachine (1) according to one of the preceding claims, characterized in that the axial length (I) of the fin (42) is less than that (L) of the blades (40). 12. Turbomachine (1) according to one of the preceding claims, characterized in that the transverse profile of the fin (42) has a camber and/or a point of inflection. 13. Turbomachine (1) according to one of the preceding claims, characterized in that the row of blades (40) comprises a plurality of fins (42) of which at least two fins (42) differ in their profile, their radial position , their circumferential length, their thickness, their shape and/or their method of manufacture. 14. Turbomachine (1) according to one of the preceding claims, characterized in that the fin (42) is welded to the blade (40) from which it extends or the fin (42) and the blade (40 ) are machined together in the same stock. 15. Turbomachine (1) according to one of the preceding claims, characterized in that all the blades (40) of the row of blades (40) and the fin(s) (42) are in one piece, obtained by the machining of a single crude or obtained by additive manufacturing. 16. Turbomachine (1) according to one of the preceding claims, characterized in that the fin (42) has a free end (42.6) whose axial length is at least 30% of the chord of the blade (40), preferably at least 70%, more preferably approximately 80% of the chord (C) of the blade (40). 17. Turbomachine (1) according to one of the preceding claims, characterized in that the fin (42) has a trailing edge (42.2) whose radial position corresponds to the radius (R) of the separating nose (36) .